148 Count Rumford’s Enquiry concerning the Nature of Heat , 
ture could be sensibly raised by the calorific rays from the hot 
body, the cooling of the hot body was retarded by a nearer ap- 
proach of that cold surface. 
From the results of these experiments we may safely con- 
clude, that if the hot body, instead of being a conical vessel 
covered up on all sides except its flat bottom, had been a globe, 
and if this hot globe had been suspended in the centre of another 
larger thin hollow sphere, (this last being, at the beginning of 
the experiment, at the same temperature as the air and walls of 
the room,) the vicinity of the surface of this hollow globe, to the 
surface of the hot body, would have retarded the cooling of the 
hot body, in the same manner as the cooling of the conical 
vessel No. 5 was retarded in the foregoing experiments ; and if, 
instead of inclosing the hot body in the centre of a single hollow 
sphere, of any given thickness, it were placed in the common 
centre of a number of much thinner concentric spheres, of dif- 
ferent diameters, the time of cooling would be still more retarded. 
By tracing the various operations which would take place in 
the cooling of the hot body, in this imaginary experiment, we 
shall become acquainted with the nature of those which actually 
take place, when the cooling of a hot body is prolonged by 
means of warm clothing. 
From the results of several of the foregoing experiments we 
may conclude, that, supposing the thin concentric hollow spheres 
in which the hot body is confined to be made of metal, the 
cooling will be slower, if the surfaces of these spheres are po- 
lished, than if they are unpolished, or blackened : and hence we 
might very naturally be led to suspect, (what is probably true 
in fact,) that the warmth of any kind of substance used as 
